Here’s What’s Inside an SD Card

This evening I was sorting through my Flash storage collection, trying to find a spare microSD card for a project. While digging through a pocket of my travel bag I found an SD card that was lying loose in the pocket. By the time I found it it was dead. (This is a lesson in why you should use the cases that come with the cards.)

After failing to recover the data, I popped the card out of my laptop and noticed it was coming apart. I'm never one to leave something half destroyed, so I pried open the card and looked inside. This is what I found.

This card was made by Sandisk, and it turns out that much of it was filler. All 4GB of storage fit into the black circuit board on the left and it took up less than half the space of the card. I hadn't realized it would be that small.

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Nate Hoffelder

Nate Hoffelder is the founder and editor of The Digital Reader: He's here to chew bubble gum and fix broken websites, and he is all out of bubble gum. He has been blogging about indie authors since 2010 while learning new tech skills at the drop of a hat. He fixes author sites, and shares what he learns on The Digital Reader's blog. In his spare time, he fosters dogs for A Forever Home, a local rescue group.

If you ever find an old 128k SD chip (or was is 256K? – whatever the first ones were) take a look inside it. They are not worth keeping now. You’ll find it used a lot more of the space. The contents have improved dramatically, while the case is still the same.

also you should keep in mind the mini/micro sd cards have the same board set in them as well. if you’ve ever owned 1 of those mini to full sd converter pieces all its really converting is the size of the plastic casing the inner workings are pretty much the same. im sure it saves on production costs considerably making only a single board and just scaling up the plastic case for standards.

Years ago, I took apart a 3.5″ floppy disk to show people, using a disk that had been roughly pulled out of a drive one too many times. And my point then was, “this is why you need to carry your disks in a box, because look at how easy it is to damage the disk.”

The contents of the SD are hardly a surprise — if they can get the same amount of storage on a micro card, why should they need more space on an SD? But yes, it is still cool.

There’s a huge IC fab in Singapore who does these monolithic chips on contract for major manufacturers. The process ends up being efficient and inexpensive. They use NAND flash dies sliced directly from a wafer, stack them over a base plastic, wirebond in the controller and metal contacts, then seal it in plastic.

I had always thought that bigger SD cards meant more room for memory. It probably does at extremely high capacities, but the 2 gig SanDisk SD that I tore down is exactly like your photo.